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Autoxidation of methyl linoleate: Identification of the bis‐allylic 11‐hydroperoxide
Author(s) -
Brash Alan R.
Publication year - 2000
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-000-0604-0
Subject(s) - autoxidation , chemistry , lipid peroxidation , allylic rearrangement , organic chemistry , nuclear magnetic resonance spectroscopy , antioxidant , photochemistry , catalysis
Abstract Based on the understanding of lipid peroxidation as a free radical chain reaction, over 50 yr ago the three primary products of linoleic acid autoxidation were predicted to be the 9‐, 11‐, and 13‐hydroperoxides. The 9‐ and 13‐hydroperoxides were found at the time, but formation of 11‐hydroperoxylinoleate or any other bis‐allylic fatty acid hydroperoxide has not been reported hetetofore as a product of lipid peroxidation reactions. In vitamin E‐controlled autoxidation of methyl linoleate, the 11‐hydroperoxy derivative was identified as the next most prominent primary peroxidation product after the 9‐and 13‐hydroperoxides. It was present in approximately 5–10% of the abundance of the 9‐ or 13‐hydroperoxide. The structures of 11‐hydroperoxylinoleate and its 11‐hydroxy derivative were established by high‐pressure liquid chromatography, ultraviolet spectroscopy, gas chromatography‐mass spectroscopy, and 1 H nuclear magnetic resonance spectroscopy. The 11‐hydroperoxide was not detectable in the absence of α‐tocopherol, indicating that efficient trapping of the 11‐peroxyl radical as the hydroperoxide is critical to permitting its accumulation.